# TypeDI

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[![npm version](https://img.shields.io/npm/v/@level-works/typedi)](https://npmjs.com/package/@level-works/typedi)

TypeDI is a [dependency injection](https://en.wikipedia.org/wiki/Dependency_injection) tool for TypeScript and JavaScript. With it you can build well-structured and easily testable applications in Node or in the browser.

Main features includes:

- property based injection
- constructor based injection
- singleton and transient services
- support for multiple DI containers

## Installation

> Note: This installation guide is for usage with TypeScript, if you wish to use
> TypeDI without Typescript please read the documentation about how get started.

To start using TypeDI install the required packages via NPM:

```bash
npm install typedi reflect-metadata
```

Import the `reflect-metadata` package at the **first line** of your application:

```ts
import 'reflect-metadata';

// Your other imports and initialization code
// comes here after you imported the reflect-metadata package!
```

As a last step, you need to enable emitting decorator metadata in your Typescript config. Add these two lines to your `tsconfig.json` file under the `compilerOptions` key:

```json
"emitDecoratorMetadata": true,
"experimentalDecorators": true,
```

Now you are ready to use TypeDI with Typescript!

## Basic Usage

```ts
import { Container, Service } from '@levelworks/typedi';

@Service()
class ExampleInjectedService {
  printMessage() {
    console.log('I am alive!');
  }
}

@Service()
class ExampleService {
  constructor(
    // because we annotated ExampleInjectedService with the @Service()
    // decorator TypeDI will automatically inject an instance of
    // ExampleInjectedService here when the ExampleService class is requested
    // from TypeDI.
    public injectedService: ExampleInjectedService
  ) {}
}

const serviceInstance = Container.get(ExampleService);
// we request an instance of ExampleService from TypeDI

serviceInstance.injectedService.printMessage();
// logs "I am alive!" to the console
```

## Documentation

The detailed usage guide and API documentation for the project can be found:

- at [docs.typestack.community/typedi][docs-stable]
- in the `./docs` folder of the repository

[docs-stable]: https://docs.typestack.community/typedi/
[docs-development]: https://docs.typestack.community/typedi/v/develop/

## Why the fork?

The only activity on [the original typedi](https://github.com/typestack/typedi)
was by bots, not by maintainers. Because of this lack of maintenance, no release
has been made since Jan 15, 2021 even though bugfixes have been merged into it's
develop branch.

This fork is solely to have the most recent state of
[typedi](https://npmjs.com/package/typedi) available on npmjs. Should the
original typedi receive updates again, this fork should track those instead of
implementing other behavior.

## Contributing

Please read our [contributing guidelines](./CONTRIBUTING.md) to get started.